1. Technical Field
The present invention relates to a projector that projects as an image a light flux modulated, for example, by a reflective liquid crystal panel.
2. Related Art
There is a projector in which a cross dichroic mirror separates the light flux from an illumination system into a plurality of color light fluxes, which are then guided to respective optical paths and illuminate three reflective liquid crystal panels disposed in the optical paths for the respective colors, and the color light fluxes modulated by the three reflective liquid crystal panels are combined in a cross dichroic prism (see JP-A-2007-127851 and JP-A-2004-240022, for example).
The projector disclosed in JP-A-2004-240022 has a structure in which a first flat plane perpendicular to two dichroic mirrors that form a cross dichroic mirror for color separation is perpendicular to a second flat plane perpendicular to two optical-path deflecting mirrors adjacent to the cross dichroic mirror in order to reduce the size of the optical system.
In the projector disclosed in JP-A-2007-127851, illumination light incident on two dichroic mirrors that form a cross dichroic mirror is P-polarized light, which makes it difficult to increase the efficiency at which target color light is separated when the illumination light is reflected off the dichroic mirrors. To intentionally increase the color separation efficiency through reflection, an expensive cross dichroic mirror is required.
On the other hand, in the projector disclosed in JP-A-2004-240022, no consideration of the plane of polarization is made for light fluxes incident on the cross dichroic mirror, polarizing beam splitters and other components, which makes it difficult to achieve bright illumination because the efficiencies at which the polarized light is reflected, separated, and otherwise processed decrease. Further, since polarizing beam splitter cubes facing respective reflective liquid crystal panels are used, increase in temperature causes thermal distortion in the glass members, which then results in change in the state of polarization. Further, increase in the angle of light results in decrease in contrast due to the dependence of the polarized light separation characteristics of dielectric multilayer films on the angle.